1. Field of the Invention
This invention relates to an image reader, and a control method and a control program for the same.
2. Description of the Related Art
Conventionally, there have been proposed image readers equipped with an automatic document feeder (hereinafter, ADF) which include a moving original reading mode and a stationary original reading mode as a reading mode using the ADF.
The moving original mode is a mode in which an original reading section on an image reader side is fixed at a predetermined reading position to read originals while the originals are fed by the ADF at a constant speed. The stationary original mode is a mode in which an original is fed onto a platen glass by the ADF and fixed on the platen glass and the original reading section reads the original while moving.
As such an image reader having the moving original mode and the stationary original mode, there has been known an image reader that changes the moving original mode to the stationary original mode in a case where dust is detected during the execution of a job of the moving original mode, in order to maintain the quality of read images (see Japanese Laid-open Patent Publication (Kokai) No. 2003-333290).
Also, there has been known an image processing apparatus that performs dust correction processing so that dust which is detected in the moving original mode becomes less conspicuous on an image to be printed (see Japanese Laid-open Patent Publication (Kokai) No. 2003-348336).
However, in the above-described image reader that changes the moving original mode to the stationary original mode when dust is detected during the execution of the job of the moving original mode, there sometimes occurs such a case where the moving original of a subsequent original has already been started at an instant when the reading mode of the subsequent original is tried to be changed to the stationary original mode. This necessitated processing such as interrupting the job of the moving original mode and discarding the already read image in order to re-read the same original.
Further, if the correction is performed so that the dust which is detected in an interval of the fed originals (sheet-to-sheet interval) during the execution of the job of the moving original mode becomes less conspicuous, there is a limit to the correctable number of dusts.
In a case where the job of the moving original mode is executed for a long time, the number of dusts detected at the reading position increases, and if the sheet-to-sheet interval is short, part of the detected dusts might not be corrected. This may possibly result in the occurrence of streaks or the like in a read image.